socket.io 判断用户是在线还是离线 [英] socket.io determine if a user is online or offline

问题描述

我们可以通过这个代码追踪连接是建立还是断开

We can trace if a connection is established or disconnected by this code

console.log('a user connected');
    socket.on('disconnect', function () {
        console.log('user disconnected');
    });

嗯，没问题.但是我们如何确定哪些用户已连接或脱机.我的客户端是用 PHP/HTML 编写的，所以他们有一个用户 ID.

Well, its fine. But how can we determine what user connected or gone offline. My client is written in PHP/HTML so they have a user ID.

推荐答案

如果您的客户端有特定的用户 ID，他们需要将它们发送到 socket.io 服务器.例如.在客户端你可以做

If your clients have specific user IDs they need to send them to socket.io server. E.g. on client side you can do

<script>
 const socket = io();
 socket.emit('login',{userId:'YourUserID'});
</script>

在服务器上你会放一些类似的东西

And on server you will put something like

const users = {};
io.on('connection', function(socket){
  console.log('a user connected');

  socket.on('login', function(data){
    console.log('a user ' + data.userId + ' connected');
    // saving userId to object with socket ID
    users[socket.id] = data.userId;
  });

  socket.on('disconnect', function(){
    console.log('user ' + users[socket.id] + ' disconnected');
    // remove saved socket from users object
    delete users[socket.id];
  });
});

现在您可以将套接字 ID 与您的用户 ID 配对并使用它.

Now you can pair socket ID to your user ID and work with it.

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